Analysis and correction method of water, salt and nutrients based on in-situ soil sampling calibrator

Abstract

The present invention discloses a method for analyzing and correcting water, salt and nutrients based on an in-situ soil sampling calibrator, and the steps are as follows: when analyzing and correcting in-situ soil moisture, the in-situ soil sampling calibrator takes samples; according to the initial mass water content value in the soil sample information data, calibration is performed through gradient setting, frequency data collection and integration, and a moisture correction curve is generated by fitting; when analyzing and correcting in-situ soil salt, the calibrator takes samples; calibration treatment is performed under each salt gradient for different soil samples, and statistical analysis is performed on the salt data of the soil samples, and a salt correction curve is generated by fitting; in the process of analyzing and correcting in-situ soil nutrients, the calibrator is used to simulate the field environment; and the nutrient sensor is used to calibrate the simulant to obtain a nutrient primary correction curve. The inventive method uses a calibrator to obtain in-situ soil without destroying the soil structure, and the data collection process is standardized, and the water and salt sensors and nutrient sensors are calibrated more accurately to improve the measurement accuracy.

Description

Technical Field

[0001] The invention relates to an in-situ soil treatment technology, in particular to a water, salt and nutrient analysis and correction method based on an in-situ soil sampling calibrator. Background Art

[0002] Non-contact capacitive field sensors are increasingly used in agricultural in-situ monitoring. With the technological development of this type of sensor, it is no longer just for measuring soil moisture, but can also measure soil salinity, nutrients, etc. At the same time, the requirements for measurement accuracy are getting higher and higher.

[0003] The Chinese invention patents named "A rapid soil nutrient in-situ measurement method based on dielectric spectroscopy" with patent number ZL201611209179.7 and "A non-contact water-salt sensor based on soil texture and its test method" with patent number ZL201610244211.9 have the following technical problems in practice:

[0004] 1. In the process of analyzing and correcting soil moisture and salt, the calibration of non-contact capacitive field sensors generally uses a universal curve, or generates a correction curve based on different soil types, and then selects a universal curve or adjusts other correction curves based on the soil type where the equipment is located. Since soils from different plots may have slightly different or very different soil distributions from top to bottom even if they are geographically similar, this difference results in large errors in the actual application of capacitive field sensors;

[0005] 2. In the process of soil nutrient analysis and correction, non-contact capacitive field sensors are used. There is a lack of sampling devices that can fully simulate the energy range of the sensor. There is no dedicated collection device when generating curve conversions at different gradients with sub-standard materials, making it difficult to achieve in-situ soil water, salt, and nutrient analysis and correction. Summary of the invention

[0006] In view of the shortcomings in the prior art such as the lack of a sampling device that can fully simulate the energy range of the sensor, the lack of a dedicated collection device when performing curve conversion under different gradients, and the difficulty in realizing in-situ soil water, salt, and nutrient analysis and correction, the present invention proposes a water, salt, and nutrient analysis and correction method based on an in-situ soil sampling calibrator.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0008] The present invention provides a water, salt and nutrient analysis and calibration method based on an in-situ soil sampling calibrator, comprising the following steps:

[0009] 1) During the in-situ soil moisture analysis and calibration process, the in-situ soil sample is obtained through the in-situ soil sampling calibrator, and the loose soil sample around the in-situ soil sampling calibrator is obtained at the same time;

[0010] 2) Obtain soil sample information data through scattered soil samples;

[0011] 3) According to the initial mass moisture content in the soil sample information data, the in-situ soil sample is calibrated through gradient setting and frequency data collection, and the moisture correction curve is fitted and generated;

[0012] 4) During the in-situ soil salt analysis and correction process, multiple groups of samples are taken using the method in step 1), and each group of soil samples includes in-situ soil samples and bulk soil samples;

[0013] 5) Calibrate each group of soil samples with a corresponding salt gradient, collect statistics on the different salt data of multiple groups of soil samples, and fit and generate a salt calibration curve;

[0014] 6) During the in-situ soil nutrient analysis and calibration process, multiple in-situ soil sampling calibrators are used to simulate the field environment;

[0015] 7) Use nutrient sensors to calibrate the simulants in different in-situ soil sampling calibrators to obtain the nutrient primary calibration curve.

[0016] The in-situ soil nutrient analysis and correction process also includes the following steps:

[0017] 8) Collect loose soil samples in the field and measure the nitrate nitrogen content, mass water content and bulk density of the loose soil samples in the laboratory;

[0018] 9) Compare the in-situ soil data actually collected in the field with the data measured in the laboratory in step 8), and generate a nutrient secondary calibration curve by fitting to complete the field calibration of the nutrient sensor.

[0019] Steps 1) to 2) are as follows:

[0020] The sampling position of the in-situ soil sampling calibrator is determined to be centered on the water and salt sensor installed in the field, with an outward radius of 20 cm to 200 cm;

[0021] At the same position as the detection depth of the water-salt sensor, peel off the covering soil, and place the in-situ soil sampling calibrator with large and small ring knives with the ring knife end facing downward, and press it into the soil perpendicularly to the soil surface through the pressing device until the position indicator line of the in-situ soil sampling calibrator coincides with the soil surface;

[0022] Dig the in-situ soil sampling calibrator out of the soil, remove the large ring knife and the small ring knife, and then smooth it so that the soil sample in the in-situ soil sampling calibrator is flush with the outer edge of the in-situ soil sampling calibrator;

[0023] Take loose soil samples, place them in an aluminum box, weigh them, dry them, and weigh them again to calculate the soil sample information data.

[0024] Step 3) The gradient setting is to perform mass moisture gradient processing on the in-situ soil sample. When the initial mass moisture content is greater than or equal to 0 and less than or equal to 60% of the field water holding capacity, the positive addition method is used; when the initial mass moisture content is greater than the field water holding capacity, the negative addition method is used; when the initial mass moisture content is greater than 60% of the field water holding capacity and less than or equal to the field water holding capacity, the mixed method is used;

[0025] When the positive addition method is adopted, the thin wall of the cup ring in the water adding auxiliary component is inserted into the outer cylinder of the in-situ soil sampling calibrator, and the thick wall inner side of the cup ring is flush with the inner side of the outer cylinder after the insertion, and the sealing is performed by the sealing member in the first annular groove between the thin wall and the thick wall; the plugging member in the water adding auxiliary component is placed in the inner cylinder of the in-situ soil sampling calibrator, and the sealing is performed by the sealing member in the second annular groove of the plugging member;

[0026] After the above operation is completed, distilled water is added to the in-situ soil sample according to the set mass moisture content of different gradients, and the mass moisture content of the in-situ soil sample under each gradient is calculated until saturation is reached; and a moisture calibration curve is generated using the measured data points.

[0027] Step 5) is as follows:

[0028] The water-salt sensor is used to collect data of the in-situ soil sample in the in-situ soil sampling calibrator, calculate the volumetric salt ion content VSIC, record the corresponding salt EC value, and save the initial data points of the VSIC value and the salt EC value;

[0029] Sampling, the number is ≥ 6 groups. If there is a gradient in the EC values ​​of all groups, the test experiment is directly carried out; when the EC values ​​of all groups are uniform and have no gradient, according to the initial data of the EC values ​​of the in-situ soil samples, salt solutions of corresponding concentrations are added to the in-situ soil samples of each group;

[0030] The water-salt sensor was used to collect data from in-situ soil samples after adding salt solutions of different concentrations, and the VSIC value was calculated.

[0031] The VSIC values ​​and the corresponding salt EC values ​​were combined to form data points to generate a salt calibration curve.

[0032] Steps 6) to 7) are as follows:

[0033] In the process of in-situ soil nutrient analysis and calibration, multiple standard columns are prepared, that is, secondary standard substances are loaded into the interlayer between the outer cylinder and the inner cylinder of multiple in-situ soil sampling calibrators. The secondary standard substances have the same material ratio as the secondary standard substances used in the field to simulate the field environment;

[0034] Carry out preliminary calibration, add water to the secondary standard substances in different calibrators to form mass water contents of 5%, 10%, 15%, 20%, 25%, and 30%, respectively, and let stand for a specified time;

[0035] Use nutrient sensors to measure the frequency value of substandard substances, and simultaneously measure the frequency values ​​of air and pure water;

[0036] The gradient frequency values ​​of air, pure water and each mass water content are used as basic values ​​to participate in the calculation of the dielectric function frequency scale index characteristic FSIC to generate a nutrient primary correction curve;

[0037] ;

[0038] Among them, f 土壤 is the frequency value of the soil, f 纯水 is the frequency value of pure water, f 空气 is the frequency value of air.

[0039] Step 8) Collecting scattered soil samples in the field is as follows:

[0040] Sampling lateral position: Randomly select 3 to 5 points for sampling within a radius of 1.0m from the nutrient sensor;

[0041] Sampling longitudinal position: The longitudinal depth should be consistent with the sensing range of the nutrient sensor.

[0042] The main body of the in-situ soil sampling calibrator is a double-layer tube structure arranged axially concentrically, one axial end of the double-layer tube structure is open, and the bottom between the layers at the other end is an annular bottom with a through hole; the bottom of the inner tube of the double-layer tube is open, and a position indicator line is provided on the surface of the outer tube.

[0043] The in-situ soil sampling calibrator also has a ring knife assembly, including a large ring knife and a small ring knife which are separately arranged, wherein the large ring knife is detachably mounted on the upper edge of the outer cylinder, and the small ring knife is detachably mounted on the upper edge of the inner cylinder; the inner wall of the large ring knife forms a straight cylinder with the inner wall of the outer cylinder, and the upper edge of the outer wall of the large ring knife has a frustum surface; the outer wall of the small ring knife forms a straight cylinder with the outer wall of the inner cylinder; the upper edge of the inner wall of the small ring knife has a frustum surface.

[0044] The in-situ soil sampling calibrator also has a water adding auxiliary component, including a cup ring and a plug which are separately arranged, wherein the cup ring is detachably mounted on the upper edge of the outer tube, and the plug is detachably inserted into the upper part of the inner tube; the cup ring includes two parts, a thin wall and a thick wall, which are integrally connected, and a first annular groove for setting a seal is provided between the two parts; the upper part of the plug is a first handle, and the lower part is reduced in diameter to form a cylindrical plug which cooperates with the inner side of the inner tube, and a second annular groove for setting a seal is provided at the reduced diameter position.

[0045] The present invention has the following beneficial effects and advantages:

[0046] 1. When the method of the present invention is used to generate a soil moisture calibration curve and a salt calibration curve, an in-situ soil sample can be obtained without destroying the soil structure due to the use of a newly designed in-situ soil sampling calibrator. The calibration curve of the water-salt sensor is generated by fitting according to the real environment in which the water-salt sensor is located, thereby improving the measurement accuracy of the water-salt sensor.

[0047] 2. The frequency field sensing range radius of the in-situ soil sampling calibrator in the present invention matches the sensing range of the water and salt sensor and the nutrient sensor, which can calibrate the water and salt sensor more accurately and effectively, has strong practicality, and standardizes the data collection process;

[0048] 3. The present invention realizes the calibration of sensors for in-situ soil moisture, salt, and nutrient multi-factor indicators based on an in-situ soil sampling calibrator, thereby improving the measurement accuracy of water and salt sensors and nutrient sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 A top view of the in-situ soil sampling and calibration device of the present invention;

[0050] Figure 2 It is a front cross-sectional view of the in-situ soil sampling and calibration device of the present invention;

[0051] Figure 3 A bottom view of the in-situ soil sampling calibrator of the present invention;

[0052] Figure 4 A top view of the plugging of the water adding auxiliary component of the in-situ soil sampling and calibration device of the present invention;

[0053] Figure 5 It is a front cross-sectional view of the plugging of the water adding auxiliary component of the in-situ soil sampling and calibration device of the present invention;

[0054] Figure 6 A bottom view of the plugging of the water adding auxiliary component of the in-situ soil sampling and calibration device of the present invention;

[0055] Figure 7 It is a front cross-sectional view of the cup ring of the water adding auxiliary component of the in-situ soil sampling and calibration device of the present invention;

[0056] Figure 8 A bottom view of the cup ring of the water adding auxiliary component of the in-situ soil sampling calibrator of the present invention;

[0057] Fig. 9 It is a front cross-sectional view of a small ring knife of the in-situ soil sampling and calibration device of the present invention;

[0058] Fig.10 A bottom view of the small ring knife of the in-situ soil sampling calibrator of the present invention;

[0059] Fig.11 It is a front cross-sectional view of the large ring knife of the in-situ soil sampling and calibration device of the present invention;

[0060] Fig.12 A bottom view of the large ring knife of the in-situ soil sampling calibrator of the present invention;

[0061] Fig.13 It is a front cross-sectional view of the pressing device of the in-situ soil sampling and calibration device of the present invention;

[0062] Fig.14 A bottom view of the pressing device of the in-situ soil sampling and calibration device of the present invention;

[0063] Fig.15 A top view of the pressing device of the in-situ soil sampling and calibration device of the present invention;

[0064] Fig.16 This is an example diagram of the clay moisture calibration curve in the method of the present invention;

[0065] Fig.17 This is an example diagram of the soil moisture calibration curve in the method of the present invention;

[0066] Fig.18 This is an example diagram of the sand soil moisture calibration curve in the method of the present invention;

[0067] Fig.19 This is an example diagram of the salt correction curve in the method of the present invention;

[0068] Fig. 20 This is an example diagram of a nutrient primary calibration curve in the method of the present invention;

[0069] Fig.21 This is an example diagram of the nutrient secondary correction curve in the method of the present invention.

[0070] Among them, 1 is an outer cylinder, 2 is an inner cylinder, 3 is an annular bottom, 4 is a through hole, 5 is a large ring knife, 6 is a small ring knife, 7 is a cup ring, 701 is a thin wall, 702 is a thick wall, 703 is a first annular groove, 8 is a plug, 801 is a cylindrical plug, 802 is a first handle, 803 is a second annular groove, 9 is a pressing device, 901 is a disk body, 902 is a connecting column, 903 is a second handle, and 904 is an air hole. DETAILED DESCRIPTION

[0071] The present invention will be further described below in conjunction with the accompanying drawings.

[0072] The present invention provides a water, salt and nutrient analysis and calibration method based on an in-situ soil sampling calibrator, comprising the following steps:

[0073] 1) During the in-situ soil moisture analysis and calibration process, the in-situ soil sample is obtained through the in-situ soil sampling calibrator, and the loose soil sample around the in-situ soil sampling calibrator is obtained at the same time;

[0074] 2) Obtain soil sample information data through scattered soil samples;

[0075] 3) According to the initial mass moisture content in the soil sample information data, the in-situ soil sample is calibrated through gradient setting and frequency data collection, and the moisture correction curve is fitted and generated;

[0076] 4) During the in-situ soil salt analysis and correction process, multiple groups of samples are taken using the method in step 1), and each group of soil samples includes in-situ soil samples and bulk soil samples;

[0077] 5) Calibrate each group of soil samples with a corresponding salt gradient, collect statistics on the different salt data of multiple groups of soil samples, and fit and generate a salt calibration curve;

[0078] 6) During the in-situ soil nutrient analysis and calibration process, multiple in-situ soil sampling calibrators are used to simulate the field environment;

[0079] 7) Use nutrient sensors to calibrate the simulants in different in-situ soil sampling calibrators to obtain the nutrient primary calibration curve.

[0080] The in-situ soil nutrient analysis and correction process also includes the following steps:

[0081] 8) Collect loose soil samples in the field and measure the nitrate nitrogen content, mass water content and bulk density of the loose soil samples in the laboratory;

[0082] 9) Compare the in-situ soil data actually collected in the field with the data measured in the laboratory in step 8), and generate a nutrient secondary calibration curve by fitting to complete the field calibration of the nutrient sensor.

[0083] The purpose of the method of the present invention is to construct a proprietary curve of the sensor according to the real environment in which the sensor is located. By adopting an in-situ sampling method, each sensor can be calibrated to produce a proprietary curve, thereby improving the measurement accuracy of the sensor.

[0084] The in-situ soil sampling calibrator (hereinafter referred to as "calibrator") used in the method of the present invention has a structure as follows: Figures 1 to 15 As shown, the main body is a double-layer cylinder structure arranged axially concentrically, one axial end of the double-layer cylinder structure is open, and the bottom between the layers at the other end is an annular bottom 3 with a through hole 4; the bottom of the inner cylinder 2 of the double-layer cylinder is open, and the surface of the outer cylinder 1 is provided with a position indicator line.

[0085] The calibrator also has a ring knife assembly, including a large ring knife 5 and a small ring knife 6 which are separately arranged, wherein the large ring knife 5 is detachably installed on the upper edge of the outer cylinder 1, and the small ring knife 6 is detachably installed on the upper edge of the inner cylinder 2; the inner wall of the large ring knife 5 forms a straight cylinder with the inner wall of the outer cylinder 1, and the upper edge of the outer wall of the large ring knife 5 has a frustum surface; the outer wall of the small ring knife 6 forms a straight cylinder with the outer wall of the inner cylinder 2; the upper edge of the inner wall of the small ring knife 6 has a frustum surface.

[0086] The calibrator also has a water-adding auxiliary component, including a cup ring 7 and a plug 8 that are separately arranged, wherein the cup ring 7 is detachably installed on the upper edge of the outer tube 1, and the plug 8 is detachably inserted into the upper part of the inner tube 2; the cup ring 7 includes two parts, a thin wall 701 and a thick wall 702 that are integrally connected, and a first annular groove 703 for setting a seal is provided between the two; the upper part of the plug 8 is a first handle 802, and the lower part is reduced in diameter to form a cylindrical plug 801 that cooperates with the inner side of the inner tube 2, and a second annular groove 803 for setting a seal is provided at the reduced diameter position.

[0087] The calibrator also has a pressing device 9, the lower part of which is a disk body 901 that can cover the bottom of the double-layer tube. A connecting column 902 is provided in the middle of the disk body 901, and the end of the connecting column 902 is reduced in diameter to form a second handle 903; an air hole 904 is provided on the disk body 901.

[0088] The calibrator is used in the water, salt and nutrient analysis and correction method based on the in-situ soil sampling calibrator. Steps 1) to 2) of the method are specifically as follows:

[0089] The sampling position of the in-situ soil sampling calibrator is determined to be centered on the water and salt sensor installed in the field, with an outward radius of 20 cm to 200 cm;

[0090] At the same position as the detection depth of the water-salt sensor, peel off the covering soil, and place the in-situ soil sampling calibrator with large and small ring knives with the ring knife end facing downward, and press it into the soil perpendicularly to the soil surface through the pressing device until the position indicator line of the in-situ soil sampling calibrator coincides with the soil surface;

[0091] Dig the in-situ soil sampling calibrator out of the soil, remove the large ring knife and the small ring knife, and then smooth it so that the soil sample in the in-situ soil sampling calibrator is flush with the outer edge of the in-situ soil sampling calibrator;

[0092] Take loose soil samples, place them in an aluminum box, weigh them, dry them, and weigh them again to calculate the soil sample information data.

[0093] The soil sample information data includes the initial mass moisture content of the soil sample, the weight of the calibrator, the initial weight of the soil sample, the field water holding capacity of the soil sample, the location of the soil sample and many other data. The calibration is performed according to the initial mass moisture content value of the soil sample.

[0094] The calibration method is the gradient setting in step 3), which is to perform mass moisture gradient processing on the in-situ soil sample. When the initial mass moisture content is greater than or equal to 0 and less than or equal to 60% of the field water holding capacity, the positive addition method is used; when the initial mass moisture content is greater than the field water holding capacity, the negative addition method is used; when the initial mass moisture content is greater than 60% of the field water holding capacity and less than or equal to the field water holding capacity, the mixed method is used;

[0095] When the positive addition method is adopted, the thin wall 701 of the cup ring 7 in the water adding auxiliary component is inserted into the outer cylinder 1 of the calibrator. After the insertion, the inner side of the thick wall 702 of the cup ring 7 is flush with the inner side of the outer cylinder, and the seal is performed by the seal in the first annular groove 703 provided on the inner side between the thin wall 701 and the thick wall 702; the plug 8 in the water adding auxiliary component is placed on the inner cylinder 2 of the calibrator, and the seal is performed by the seal in the second annular groove 803 of the plug 8;

[0096] After the above operation is completed, distilled water is added to the in-situ soil sample according to the set mass moisture content of different gradients, and the mass moisture content of the in-situ soil sample under each gradient is calculated until saturation is reached; and a moisture calibration curve is generated using the measured data points.

[0097] Step 5) is as follows:

[0098] The water-salt sensor is used to collect data of the in-situ soil sample in the in-situ soil sampling calibrator, calculate the volume salt ion content VSIC (Volume Salt Ion Content), and record the corresponding salt EC value (Electrical Conductivity), and save the initial data points of the VSIC value and the salt EC value;

[0099] Sampling, the number is ≥ 6 groups, if there is a gradient in the salt EC value of all groups, the test experiment will be carried out directly;

[0100] When the EC values ​​of salt in all groups are uniform and have no gradient, according to the initial data of the EC values ​​of salt in situ soil samples, salt solutions of corresponding concentrations are added to each group of in situ soil samples to form a gradient;

[0101] The water-salt sensor was used to collect data from in-situ soil samples after adding salt solutions of different concentrations, and the VSIC value was calculated.

[0102] The VSIC values ​​and the corresponding salt EC values ​​were combined to form data points to generate a salt calibration curve.

[0103] Steps 6) to 7) are as follows:

[0104] In the process of in-situ soil nutrient analysis and calibration, multiple standard columns are prepared, that is, secondary standard substances are loaded into the interlayer between the outer cylinder and the inner cylinder of multiple in-situ soil sampling calibrators. The secondary standard substances have the same material ratio as the secondary standard substances used in the field to simulate the field environment;

[0105] Carry out preliminary calibration, add water to the secondary standard substances in different calibrators to form mass water contents of 5%, 10%, 15%, 20%, 25%, and 30%, respectively, and let stand for a specified time;

[0106] Use nutrient sensors to measure the frequency value of substandard substances, and simultaneously measure the frequency values ​​of air and pure water;

[0107] The gradient frequency values ​​of air, pure water and each mass water content are used as basic values ​​to participate in the calculation of the frequency scale index characteristics FSIC (Frequency Scaled Index Characteristics) of the dielectric function. The FSIC and nitrate nitrogen content are used as data points to generate a nutrient primary correction curve.

[0108] ;

[0109] Among them, f 土壤 is the frequency value of the soil, f 纯水 is the frequency value of pure water, f 空气 is the frequency value of air.

[0110] Step 8) Use the soil drilling method to collect field soil samples, specifically:

[0111] Sampling lateral position: Randomly select 3 to 5 points for sampling within a radius of 1.0m from the nutrient sensor;

[0112] Sampling longitudinal position: The longitudinal depth should be consistent with the sensing range of the nutrient sensor.

[0113] 1. Moisture analysis and correction method

[0114] In the process of in-situ soil water and salt analysis and calibration, the in-situ soil sampling method is the same. After determining the buried position of the calibrator, record the number of each calibrator, weigh it and keep a record to obtain the calibrator mass M. 标定器 ;

[0115] During moisture analysis and calibration, it is sufficient to collect an in-situ soil sample.

[0116] At the same position as the detection depth of the water and salt sensor, peel off the covering soil. The peeling depth is calculated by subtracting 5.0cm from the depth. For example, a 10cm sensor needs to peel off 10-5.0cm of soil before sampling.

[0117] Place the knife end of the calibrator with the large and small knife rings downward, and drive it vertically into the soil layer with the handle and hammer of the pressing device until the position indicator line on the calibrator coincides with the ground after stripping, and then stop knocking;

[0118] Dig the calibrator out of the soil layer, and remember not to rotate or pull it out when taking it out;

[0119] Use a spatula to smooth out the excess soil, remove the large and small ring knives, and further smooth out the excess soil to make it flush with the edge of the calibrator tube;

[0120] Take the soil in the center part, i.e. the inner tube 2, and put it in an aluminum box for later use. Use a soil drill, brush, sponge brush or other tools to clean the inner tube 2. Use a towel or brush to clean the outside and bottom of the calibrator.

[0121] Weigh and record the weight of the treated soil column, i.e., the calibrator containing the soil sample, to obtain M 标定器+湿土 .

[0122] Information confirmed:

[0123] Number the aluminum box, weigh it and record the mass M of the aluminum box 铝盒 ;

[0124] Take a loose soil sample (referring to the soil sample around the calibrator during in-situ soil sampling) and place it in an aluminum box, about 30g-50g;

[0125] Weigh the aluminum box containing the soil sample and record the mass M of the aluminum box and wet soil. 铝盒+湿土 ;

[0126] Treat with alcohol burning method or drying method, and measure the mass M of aluminum box + dry soil 铝盒+干土 .

[0127] Calculate the parameters of soil sample:

[0128] Water content by mass: θ m =(M 铝盒+湿土 -M 铝盒+干土 ) / (M 铝盒+干土 -M 铝盒 );

[0129] Wet soil mass in the calibrator: M 标定器内湿土 =M 标定器+湿土 -M 标定器 ;

[0130] Dry soil mass in the calibrator: M 标定器内干土 =M 标定器内湿土 / (1+θ m );

[0131] Soil bulk density: C=M 标定器内干土 / V 标定器容积 ;

[0132] Volumetric water contentθ V =θ m ×C.

[0133] The calibration method is determined according to the initial mass moisture content of the soil sample:

[0134] Method 1: Positive addition method, which is applicable to the case where the initial mass water content of the soil sample is small (greater than or equal to 0, less than or equal to 60% field water holding capacity);

[0135] The initial mass moisture content of the soil sample is used as the initial gradient to divide the gradient upwards, and each gradient needs to be controlled within 5%±1%;

[0136] Divide the gradient according to the initial mass water content (extend at least two gradients upward), add distilled water to the calibrator according to the set gradient, let it stand, test, and record until the soil reaches the saturation state; sandy soil is allowed to stand for 10 minutes, loam is allowed to stand for 20 minutes, and clay is allowed to stand for 30 minutes;

[0137] The water and salt sensor is used to collect the frequency values ​​at each gradient, and the normalized parameter SF values ​​are calculated respectively:

[0138] SF = (Fa-Fs) / (Fa-Fw);

[0139] Among them, Fa is the frequency value measured in pure air environment at standard temperature, Fs is the frequency value measured in soil-water mixture at standard temperature, and Fw is the frequency value measured in pure water environment under standard environment;

[0140] The SF value and the mass water content of the corresponding gradient are saved as corresponding data points, and the mass water content is converted into volume water content;

[0141] All measured data points are used for fitting to generate a moisture correction curve.

[0142] Method 2: Negative addition method, which is suitable for the situation where the initial mass moisture content of the soil sample is large (greater than the field water holding capacity), and all kinds of soil are applicable.

[0143] The initial mass water content of the soil sample in the calibrator is used as the initial gradient to divide the gradient downwards. Each gradient needs to be controlled within 7%±2%;

[0144] Divide the gradients according to the initial mass moisture content (extend at least two gradients downward), carry out water reduction treatment one by one according to the designed gradient, and complete the test and data recording work after each water reduction treatment; the drying temperature of the water reduction treatment is 50-55℃, and the drying time is adjusted according to the soil type and initial mass moisture content, and the mass of the soil column when the drying is completed is used as the measurement basis, until the mass moisture content of the soil sample in the soil column reaches 5%-7%;

[0145] The water and salt sensor is used to collect the frequency values ​​at each gradient, and the normalized parameter SF values ​​are calculated respectively:

[0146] The SF value and the mass water content of the corresponding gradient are saved as corresponding data points, and the mass water content is converted into volume water content;

[0147] All measured data points are used for fitting to generate a moisture correction curve.

[0148] Method 3: Hybrid method:

[0149] Taking the initial mass water content of the soil sample in the calibrator as an intermediate point, the positive addition method is used upward to achieve different gradients of water content, and the negative addition method is used downward, and the data points are determined in the same way as methods one and two with the same operation steps and gradient requirements;

[0150] The data points are then fitted to generate a moisture correction curve.

[0151] 2. Salt analysis and correction method

[0152] Sampling: the number of samples shall be ≥ 6 groups, each group shall include loose soil samples and in-situ soil samples; the sampling position shall be centered on the water-salt sensor, with a radius within the range of 200 mm to 2000 mm; the in-situ soil sampling method shall be the same as the in-situ soil sampling method for moisture correction;

[0153] Determination of initial soil sample information: The EC value of the salt content of the bulk soil sample is measured and used to represent the EC value of the salt content of the in-situ soil samples of the same group;

[0154] The water-salt sensor is used to collect data from the in-situ soil sample, and the volumetric salt ion content VSIC value is calculated and saved as a paired initial data point with the above-mentioned salt EC value;

[0155] Calibration method:

[0156] If there is a gradient in the EC value of salt (EC difference greater than 0.1dS / m), the test experiment is directly carried out;

[0157] If the EC value of salt is uniform and has no gradient (EC difference is less than or equal to 0.1 dS / m), add mixed salt solution to the in-situ soil sample to adjust the EC value of salt. According to the EC value of salt of soil sample, add salt solution of different concentrations to the soil column to form a uniform EC gradient between every two in-situ soil samples.

[0158] The exchange time between soil salt and colloid varies with soil types. Sandy soil needs to be left standing for 0.25 hours, loamy soil needs to be left standing for 0.5 hours, and clay soil needs to be left standing for 1 hour.

[0159] The in-situ soil samples were measured using a water-salt sensor, the frequency values ​​were collected and the VSIC values ​​were calculated;

[0160] The in-situ soil samples were sampled and the salt EC values ​​were measured according to the salt EC;

[0161] The VSIC value and salt EC value were saved as corresponding data points, and a salt calibration curve was generated by fitting.

[0162] 3. Nutrient analysis and correction methods

[0163] In the present invention, the calibrator filled with the secondary standard substance is called a standard column.

[0164] To prepare multiple standard columns:

[0165] After pickling, drying and sieving, the substandard materials are placed in different mesh sizes;

[0166] The substandard material in the standard column must have the same material ratio as the substandard material used on site. In this embodiment, the selected substandard material is quartz sand, and the target soil is loam. The substandard material is loaded into the calibrator, and the mesh ratio of the substandard material is: 70 (exclusive) to 80 (inclusive) mesh 20%, 80 (exclusive) to 90 (inclusive) mesh 20%, 90 (exclusive) to 100 (inclusive) mesh 20%, 100 (exclusive) to 110 (inclusive) mesh 20%, 110 (exclusive) to 120 (inclusive) mesh 20%;

[0167] In order to simulate the on-site environment, the sub-standard substance needs to be compacted after being loaded into the calibrator. The calibrator filled with the sub-standard substance is called a standard column.

[0168] Initial calibration:

[0169] Add water to the secondary standard substances in different calibrators to form a mass water content of 5%, 10%, 15%, 20%, 25%, and 30%, respectively, and let it stand for two minutes;

[0170] Use nutrient sensors to measure the frequency value of substandard substances, and simultaneously measure the frequency values ​​of air and pure water;

[0171] The frequency values ​​of air, pure water and each mass water content gradient are used as basic values ​​to participate in the calculation and fit to generate a nutrient primary correction curve.

[0172] Field calibration:

[0173] Soil sampling (bulk soil sampling) is carried out by soil drilling method;

[0174] Sampling lateral position: Randomly select 5 points for sampling within a radius of 1.0m from the nutrient sensor;

[0175] Sampling longitudinal position: The longitudinal depth is consistent with the sensing range of the nutrient sensor. For example, the nutrient sensor takes soil samples within the range of 5cm~15cm at the "10cm" position, 15~25cm at the "20cm" position, 25~35cm at the "30cm" position, and 35~45cm at the "40cm" position.

[0176] Determination of nitrate nitrogen content by extraction method: Measure the nitrate nitrogen content of soil samples according to the commonly used extraction method in the laboratory;

[0177] Determination of mass moisture content and bulk density: Determination of mass moisture content and bulk density at the sampling location using common laboratory methods;

[0178] Data analysis: The nitrate nitrogen content measured in the laboratory is fitted with the nitrate nitrogen content collected by the nutrient sensor to generate a nutrient secondary calibration curve to complete the field calibration of the nutrient sensor.

[0179] In the present invention, soil is a general term, soil sample is a soil sample, loose soil is a kind of soil sample, soil column is also a kind of soil sample, but the soil column is to distinguish the original state obtained under the calibrator, so it is called soil column.

[0180] The following is an example of the moisture correction curve of clay at a depth of 30 cm in Shenhe District, Shenyang City

[0181] Measured: The mass of the calibrator is M 标定器 =287.01g;

[0182] After sampling, the measured value is: M 标定器+湿土 =668.03g;

[0183] Aluminum box quality: M 铝盒 =50g;

[0184] Aluminum box + wet soil mass: M 铝盒+湿土 =69.03g;

[0185] After drying, the mass of aluminum box + dry soil is measured: M 铝盒+干土 =68.51 g;

[0186] The calculation results show that the initial mass moisture content is: 2.8%;

[0187] Bulk density: 1.08g / cm 3 ;

[0188] Initial volume water content: 3.0%;

[0189] The moisture calibration curve is generated by using the SF value and volumetric moisture content. An example of a clay moisture calibration curve is as follows: Fig.16 shown.

[0190] An example of a soil moisture calibration curve is shown below: Fig.17 As shown, loam from Shuangliao City, Jilin Province is used; an example of sand soil moisture correction curve is as follows Fig.18 As shown, sandy soil from Wafangdian City, Liaoning Province was used.

[0191] Salt correction data: Taking the saline-alkali land in Huanghekou Town, Kenli County, Dongying City, Shandong Province as an example, three layers of in-situ soil samples with soil depths of 20cm, 40cm, and 60cm were taken to measure the initial salt EC value, which showed a gradient. Therefore, the retrieved in-situ soil column (calibrator + wet soil) was cleaned up, and then the water and salt sensors were used to collect the frequency, record the data, calculate VSIC, and finally perform data fitting. The fitting results show R 2 (Correlation) is 0.9661, reaching the application level. The EC and VSIC correction data at each soil depth are shown in Table 1, and the salt correction curve is shown in Fig.19 shown.

[0192] Table 1 shows the EC and VSIC correction data at various soil depths:

[0193]

[0194] Nutrient calibration data: The nutrient primary calibration curve is prepared in the laboratory. Fig. 20 As shown;

[0195] Field "secondary calibration" takes the Henan Xinxiang test base as an example. After 6 soil samplings, curve fitting is performed. 2 is 0.8439, reaching the application level. The nutrient secondary calibration curve data is as follows Fig.21 shown.

[0196] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A water, salt and nutrient analysis and calibration method based on an in-situ soil sampling calibrator, characterized in that The following steps are involved: 1) During the in-situ soil moisture analysis and calibration process, the in-situ soil sample is obtained through the in-situ soil sampling calibrator, and the loose soil sample around the in-situ soil sampling calibrator is obtained at the same time; 2) Obtain soil sample information data through scattered soil samples; 3) According to the initial mass moisture content in the soil sample information data, the in-situ soil sample is calibrated by gradient setting and frequency data collection. Distilled water is added to the in-situ soil sample according to the mass moisture content of different gradients set, and the mass moisture content of the in-situ soil sample under each gradient is calculated until saturation is reached; the measured data points are used to fit and generate a moisture calibration curve; 4) During the in-situ soil salt analysis and correction process, multiple groups of samples are taken using the method in step 1), and each group of soil samples includes in-situ soil samples and bulk soil samples; 5) For different groups of soil samples, a salt gradient is correspondingly calibrated, and the different salt data of multiple groups of soil samples are statistically analyzed to generate a salt calibration curve by fitting, specifically: The water-salt sensor is used to collect data of the in-situ soil sample in the in-situ soil sampling calibrator, calculate the volumetric salt ion content VSIC, record the corresponding salt EC value, and save the initial data points of the VSIC value and the salt EC value; Sampling, the number is ≥ 6 groups. If there is a gradient in the EC values ​​of all groups, the test experiment is directly carried out; when the EC values ​​of all groups are uniform and have no gradient, according to the initial data of the EC values ​​of the in-situ soil samples, salt solutions of corresponding concentrations are added to the in-situ soil samples of each group; The water-salt sensor was used to collect data from in-situ soil samples after adding salt solutions of different concentrations, and the VSIC value was calculated. The VSIC values ​​and the corresponding salt EC values ​​were used to form data points to generate a salt calibration curve; 6) During the in-situ soil nutrient analysis and calibration process, multiple in-situ soil sampling calibrators are used to simulate the field environment; 7) Use the nutrient sensor to calibrate the simulants in different in-situ soil sampling calibrators to obtain the nutrient primary calibration curve, specifically: Carry out preliminary calibration, add water to the secondary standard substances in different calibrators to form mass water contents of 5%, 10%, 15%, 20%, 25%, and 30%, respectively, and let stand for a specified time; Use the nutrient sensor to measure the frequency value of the substandard substance, and simultaneously measure the frequency value of air and pure water; The gradient frequency values ​​of air, pure water and each mass water content are used as basic values ​​to participate in the calculation of the dielectric function frequency scale index characteristic FSIC to generate a nutrient primary correction curve; ； Among them, f 土壤 is the frequency value of the soil, f 纯水 is the frequency value of pure water, f 空气 is the frequency value of air; The in-situ soil nutrient analysis and correction process also includes the following steps: 8) Collect loose soil samples in the field and measure the nitrate nitrogen content, mass water content and bulk density of the loose soil samples in the laboratory; 9) Compare the in-situ soil nitrate nitrogen content data actually collected in the field with the nitrate nitrogen content data measured in the laboratory in step 8), and fit to generate a nutrient secondary calibration curve to complete the field calibration of the nutrient sensor.

2. The water, salt and nutrient analysis and calibration method based on the in-situ soil sampling calibrator according to claim 1 is characterized in that Steps 1) to 2) are as follows: The sampling position of the in-situ soil sampling calibrator is determined to be centered on the water and salt sensor installed in the field, with an outward radius of 20 cm to 200 cm; At the same position as the detection depth of the water-salt sensor, peel off the covering soil, and place the in-situ soil sampling calibrator with large and small ring knives with the ring knife end facing downward, and press it into the soil perpendicularly to the soil surface through the pressing device until the position indicator line of the in-situ soil sampling calibrator coincides with the soil surface; Dig the in-situ soil sampling calibrator out of the soil, remove the large ring knife and the small ring knife, and then smooth it so that the soil sample in the in-situ soil sampling calibrator is flush with the outer edge of the in-situ soil sampling calibrator; Take loose soil samples, place them in an aluminum box, weigh them, dry them, and weigh them again to calculate the soil sample information data.

3. The water, salt and nutrient analysis and calibration method based on the in-situ soil sampling calibrator according to claim 1 is characterized in that: Step 3) The gradient setting is to perform mass moisture gradient processing on the in-situ soil sample. When the initial mass moisture content is greater than or equal to 0 and less than or equal to 60% of the field water holding capacity, the positive addition method is used; when the initial mass moisture content is greater than the field water holding capacity, the negative addition method is used; when the initial mass moisture content is greater than 60% of the field water holding capacity and less than or equal to the field water holding capacity, the mixed method is used; When the positive addition method is adopted, the thin wall of the cup ring in the water adding auxiliary component is inserted into the outer cylinder of the in-situ soil sampling calibrator, and the thick wall inner side of the cup ring is flush with the inner side of the outer cylinder after the insertion, and the sealing is performed by the sealing member in the first annular groove between the thin wall and the thick wall; the plugging member in the water adding auxiliary component is placed in the inner cylinder of the in-situ soil sampling calibrator, and the sealing is performed by the sealing member in the second annular groove of the plugging member; After the above operations are completed, the step of adding distilled water to the in-situ soil sample according to the set different gradients of mass water content is entered; The negative addition method uses the initial mass water content of the soil sample in the calibrator as the initial gradient to divide the gradient downward, and each gradient needs to be controlled within 7%±2%; Divide the gradient according to the initial mass moisture content, carry out water reduction treatment one by one according to the designed gradient, and complete the test and data recording work after each water reduction treatment; the drying temperature of the water reduction treatment is 50-55℃, and the drying time is adjusted according to the soil type and initial mass moisture content. The mass of the soil column when the drying is completed is used as the measurement basis, until the mass moisture content of the soil sample in the soil column reaches 5%-7%; The water and salt sensor is used to collect the frequency values ​​at each gradient, and the normalized parameter SF values ​​are calculated respectively: The SF value and the mass water content of the corresponding gradient are saved as corresponding data points, and the mass water content is converted into volume water content; All measured data points are used for fitting to generate a moisture correction curve; The mixed method uses the initial mass water content of the soil sample in the calibrator as an intermediate point, uses the positive addition method to achieve different gradients of water content upward, and uses the negative addition method downward, and uses the same operation steps and gradient requirements as methods one and two to determine the data points respectively; The data points are then fitted to generate a moisture correction curve.

4. The water, salt and nutrient analysis and calibration method based on the in-situ soil sampling calibrator according to claim 1 is characterized in that: Step 6) is as follows: During the in-situ soil nutrient analysis and calibration process, multiple standard columns are prepared, that is, secondary standard substances are loaded into the interlayer between the outer cylinder and the inner cylinder of multiple in-situ soil sampling calibrators. The secondary standard substances have the same material ratio as the secondary standard substances used in the field to simulate the field environment.

5. The water, salt and nutrient analysis and calibration method based on the in-situ soil sampling calibrator according to claim 1 is characterized in that: Step 8) Collecting scattered soil samples in the field is as follows: Sampling lateral position: Randomly select 3 to 5 points for sampling within a radius of 1.0m from the nutrient sensor; Sampling longitudinal position: The longitudinal depth should be consistent with the sensing range of the nutrient sensor.

6. The water, salt and nutrient analysis and calibration method based on the in-situ soil sampling calibrator according to claim 1 is characterized in that: The main body of the in-situ soil sampling calibrator is a double-layer tube structure arranged axially concentrically, one axial end of the double-layer tube structure is open, and the bottom between the layers at the other end is an annular bottom with a through hole; the bottom of the inner tube of the double-layer tube is open, and a position indicator line is provided on the surface of the outer tube.

7. The water, salt and nutrient analysis and calibration method based on the in-situ soil sampling calibrator according to claim 6 is characterized by: The in-situ soil sampling calibrator also has a ring knife assembly, including a large ring knife and a small ring knife which are separately arranged, wherein the large ring knife is detachably mounted on the upper edge of the outer cylinder, and the small ring knife is detachably mounted on the upper edge of the inner cylinder; the inner wall of the large ring knife forms a straight cylinder with the inner wall of the outer cylinder, and the upper edge of the outer wall of the large ring knife has a frustum surface; the outer wall of the small ring knife forms a straight cylinder with the outer wall of the inner cylinder; the upper edge of the inner wall of the small ring knife has a frustum surface.

8. The water, salt and nutrient analysis and calibration method based on the in-situ soil sampling calibrator according to claim 6 is characterized by: The in-situ soil sampling calibrator also has a water adding auxiliary component, including a cup ring and a plug which are separately arranged, wherein the cup ring is detachably mounted on the upper edge of the outer tube, and the plug is detachably inserted into the upper part of the inner tube; the cup ring includes two parts, a thin wall and a thick wall, which are integrally connected, and a first annular groove for setting a seal is provided between the two parts; the upper part of the plug is a first handle, and the lower part is reduced in diameter to form a cylindrical plug which cooperates with the inner side of the inner tube, and a second annular groove for setting a seal is provided at the reduced diameter position.

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